Process for the regulation of the elasticity modulus of highly elastic fibers and films



United States Patent 3,354,251 PROCESS FOR THE REGULATEON OF THE ELAS- TllClTY MGDULUS OF HIGHLY ELASTIC FIBERS AND FILMS Wilhelm Thoma, Cologne-Flittard, and Heinrich Rinke, Leverkusen, Germany, assignors to Farbenfabrilren Bayer Ahtiengeselischaft, Leverkusen, Germany, a German corporation No Drawing. Filed Apr. 29, 1964, der. No. 363,611 Claims priority, application Germany, May 3, 1963, F 39,645 11 Claims. (Cl. 264-210) ABSTRACT @IF THE DISCLOSURE Shaped polyurethane polymers such as filaments, are prepared from a solution of a polyurethane polymer in an inert solvent wherein the polyurethane polymer is prepared from an organic compound containing active hydrogen atoms that are reactive with NCO groups and an organic polyisocyanate, the solution being substantially free of NCO groups. To the solution is added a compound that is compatible therewith and capable of reacting with the polymer only by imparting energy thereto. The solution is then shaped through an aperture, stretched and energy is applied to cause cross-linking in the stretched condition to fix orientation.

This invention relates to a method for making highly elastic fibers and films by the isocyanate polyaddition process and more particularly to a method of regulating the elasticity modulus of highly elastic fibers and films.

This application is a continuation-in-part of U.S. patent application Ser. No. 123,128, filed July 11, 1961, and now abandoned.

It has been heretofore known to use natural or synthetic rubbers for the manufacture of highly elastic molded elements such as fibers, webs and films. By highly elastic molded elements is meant elements having an elastic elongation of from about ZOO to about 800 percent. The elastic elongation is defined by G. Wagner, Mechanisch- Technologische Textilprunfungen, pages 101-103, as the difference between total elongation and permanent elongation. Natural or synthetic fibers or strips commonly used in the textile industry in the manufacture of garments such as bathing suits, elastic stockings and the like are subjected to the disadvantages of insufiicient resistance to the action of light, oxygen, ozone, oils and fats, for example, the oils and creams used in cosmetics or in light protective agents and ointments.

It has also been known to produce highly elastic fibers having superior properties to rubber by the isocyanate polyaddition process. In particular, the stability to light and solvents, for example, chemica.s used for cleaning such as trichloroethylene, and the stability to cosmetic fats and oils are improved. For the preparation of such garments as mentioned above, it is desirable to have available fibers, films and bands exhibiting ditferent tightness. By tightness is meant a requirement for difierent tensions for the stretching of the fiber, film or band. This tension is defined as the elasticity modulus in grams per denier and is the force necessary to stretch a highly elastic element by a certain amount of the original length such as, for example, 100 percent. The possibility of regulating the elasticity modulus of soft types of fibers has been found to be of particular advantage.

It is known to orient shaped elements such as fibers and films by stretching. By this procedure, the modulus rises and the permanent elongation falls, only temporarily, until the fixed condition produced by orientation in the shaped element is reached. This fixed condition is destroyed, however, by the action of temperature for example, when washing by boiling. Also, if the shaped elements are not orientated, but are merely subjected to a final cross-linking, the increase in the elasticity modulus is insignificant.

It is therefore an object of this invention to provide an improved method for making elastic fibers It is another object of this invention to provide an improved method for making elastic fibers wherein the elasticity modulus of the fibers is regulated. It is still another object of this invention to provide an improved method for making highly elastic fibers and films having an elastic elongation of from about 206 to about 800 percent by the isocyanate polyaddition process wherein the elasticity modulus of the resulting fiber or film is regulated. It is a further object of this invention to provide a method of preparing shaped elastic fibers and films which maintains the fixed condition achieved by orientation even after subjecting the element to boiling.

The foregoing objects and others which will become apparent from the following description are accomplished in accordance with this invention, generally speaking, by providing a process for regulating the elasticity modulus of highly elastic fibers and films having an elastic elongation of from about 200 to about 800 percent from polymers produced by the isocyanate polyaddition process by incorporating into asolution of the polymers prior to the shaping operation into fibers or films a solution of a compatible substance which after forming of the polymers from solution and subsequent orientation by stretching, produces in the shaped elements a condensation or radical cross-linking by subjecting the fiber or film to the action of an energy source such as, for example, heat or radiation which fixes the orientation of the shaped element.

Thus, the invention contemplates shaping a polyurethane polymer from solution, to which has been added a compatible substance, stretching the shaped article and imparting energy to the article when in the stretched condition. The energy fixes the orientation caused by the stretching and achieves high properties. The polymer to be shaped can be prepared by either reacting the reactive components of a polyurethane polymer in the melt or in a solvent. If reacted in the melt, the reaction product is dissolved in a suitable solvent from which it is shaped. If the reaction is conducted in a solvent, the shaping can take place either from the same solvent or from a different solvent which has replaced it.

As stated previously, When orientation is accomplished in the manner known in the art, a fixed condition is reached which is permanent only so long as the element is not subjected to high temperatures and this includes boiling temperatures. In accordance with the process of this invention, the fixed condition produced by orientation due to stretching is maintained by the superimposition of a lattice of high molecular weight. By this process, the total elongation of the shaped element decreases somewhat to a certain value. However, this is not of importance with films and fibers produced from the isocyanate polyaddition process because these films and fibers have very high total elongation. Thus, the invention contemplates the introduction into the solution containing a film-forming polymer, a substance which will produce in the shaped final element a condensation or radical cross linking which will, upon orientation and the application of heat, maintain the orientation in fixed condition.

The extent of the orientation is defined in terms of the speeds of which the respective means for stretching the element are moving. That is, When the shaped element leaves the shaping device, for example, the film issuing 3 r from the spinning funnel is conveyed at a speed v over a driving arrangement and is wound at the speed v on a spool, v being larger than v In this case, the orientation defined as c is represented by the following formula The process according to the invention enables the E-moduli to be regulated by a factor of from to so that values of 0.03 to 0.4 gram per denier can be obtained with 100 percent elongation. It has been found that with increased E-moduli the permanent elongation is reduced in a desirable manner. The permanent elongation is defined as the increase in length as a percentage of the original length after elongation to a certain extent and subsequent relaxation for a certain time. There are several measuring techniques following this definition. One is employed in Examples 1 to 4 wherein the material is subjected to a 100 percent elongation lasting two minutes and to a subsequent relaxation for thirty seconds. Then the increase in length as a percentage of the original length is determined. Another measuring technique is employed in Example 5 wherein the material is subjected to a 300 percent elongation and a subsequent relaxation lasting thirty seconds, but the increase in length as a percentage of the original length is not determined earlier than after three elongation-relaxation cycles.

Generally, the process according to the invention leads to highly elastic shaped elements of which the elasticity modulus is higher by the factor 1.1 to 10 than in the unstretched condition. Elasticity moduli of 0.08-0.8 g./den. are obtained at 300% elongation and it is found that, as the elasticity is increased, the permanent elongation is reduced in desirable manner.

The measurement of the elasticity is effected with the Elasto-Tensograph described in Chirnia 16 (1962) 93-105. The elasticity modulus at 300% elongation is determined in the first stretching of the filament at 400% /min. of stretching speed, and also the elasticity value of 150% in the third relaxing cycle after being stretchedthree times to 300%.

The solutions used for the production of the highly elastic shaped elements are obtained by the isocyanate polyaddition process by the reaction of products comprising free NCO groups with an equivalent. or smaller quantity of a chain-extending agent such as polyhydric alcohols, polyamines, hydrazines and the like. Generally, the quantity of the chain-extending agent is less than that required for complete reaction with the -NCO groups. Generally, the reaction is carried out in a solvent inert to -NCO groups.

However, the polymers comprising urethane groups can also be produced in the melt by the isocyanate'polyaddition process. A mixture of a substantially linear polyhydroxyl compound and a chain extender is reacted with a polyisocyanate in the melt. The reaction can also be effected in successive steps. The melt is subsequently heated in shallow trays at from about 80 C. to about 150 C. for from about 5 minutes to about 180 minutes. After cooling, the polyurethane composition is granulated and dissolved in a solvent, e.g. dimethyl formamide, dimethyl acetamide or dimethyl sulphoxide.

Where there is an excess of NCO groups, the reaction can take place in the presence of catalysts causing the polymerization of the groups. It might also be desirable to terminate the cross-linked reaction by adding monohydric alcohols or amines to remove any free --NCO groups present.

The products containing free NCO groups utilized in accordance with this invention are prepared by reacting an organic compound containing active hydrogen atoms as determined, by the Zerewitinoff method, which atoms are reactive with -NCO groups, with an organic polyisocyanate to. prepare an -NCO terminated prepolymer. Any suitable compound can be used in reaction with the polyisocyanate such as, for example, hydroxyl polyesters, polyhydric polyalkylene ethers and polyhydric polythioethers, and polyacetals may be used in reaction with an organic polyisocyanate to form one of the initial components utilized in the practice of this invention. Of course, the hydroxyl polyester may contain urethane groups, urea groups, amide groups, chalkogen linkages such as oxygen or sulfur and the like. Thus, the term hydroxyl polyester includes not only pure polyesters but also polyester amides, polyester urethanes, polyether esters and the like.

Any suitable hydroxyl polyester may be used such as, for example, the reaction product of a polycarboxylic acid and a polyhydric alcohol. Any suitable polycarboxylic acid may be used in the preparation of a polyester such as, for example, adipic acid, succinic acid, suberic acid, sebacic acid, oxalic acid, methyladipic acid, glutaric acid, pimelic acid, azelaic acid, phthalic acid, terephthalic acid, isophthalic acid, 1,2,4-benzene tricarboxylic acid, thiodiglycollic acid, thiodipropionic acid, maleic acid, fumaric acid, citraconic acid, itaconic acid and the like. Any suitable polyhydric alcohol may be used in the reaction with the polycarboxylic acid to form a polyester such as, for example, ethylene glycol, propylene glycol, butylene glycol, hexanediol, hexanetriol, glycerine, bis- (hydroxy-methyl-cyclohexane), trimethylol propane, pentaerythritol and the like. The hydroxyl polyester should have a molecular weight of from about 500 to about 3000, an hydroxyl number of from about 30 to about 300 and an acid number of less than about 5.

Any suitable polyester amide may be used such as, for example, the reaction product of an amine or an amino alcohol with a polycarboxylic acid. Any suitable amine such as, for example, ethylene diamine, propylene diarnine and the like may be used. Any suitable amino alcohol such as, for example, beta-hydroxy ethyl amine and the like may be used. Any of the polycarboxylic acids set forth above with relation to the preparation of hydroxy polyesters may be used in the preparation of polyester amides. The polyester amides may also be prepared by the reaction of diol-diarnides such as, for example, the reaction product of adipic acid and diethanolamide, terephthalic acid-bis-propanolarnide with a dicarboxylic acid. The polyester amides should have a molecular weight, hydroxyl number and acid number comparable to polyesters.

The polyesters and the polyester amides may be reacted with isocyanates to prepare hydroxyl or amine terminated compound containing urethane and urea linkages which are suitable for use in the preparation of the spinning solution of this invention. Any suitable isocyanate which will be set forth hereinafter may be used.

Any suitable polyether ester may be used as the organic compound containing active hydrogen atoms such as, for example, the reaction product of an ether glycol and a dicarboxylic acid such as those previously mentioned with relation to the preparation of polyesters. Any suitable ether glycol may be used such as, for example, di-

ethylene glycol, triethylene glycol, 1,4-phenylene bis-hydroxy ethyl ether, 2,2-diphenyl propane-4,4-bis-hydroxy ethyl ether and the like.

Any suitable polyhydric polyalkylene ether may be used such as, for example, the condensation product of an alkylene oxide with a small amount of a compound containing active hydrogen containing groups such as, for example, water, ethylene glycol, propylene glycol, butylene glycol, amylene glycol, trimethylolpropane, glycerine, pentaerythritol, hexanetriol and the like. Any suitable alkylene oxide condensate may also be used such as, for example, the condensates of ethylene oxide, propylene oxide, butylene oxide, amylene oxide and mixtures thereof. The polyalkylene ethers prepared from tetrahydrofuran may be used. The polyhydric polyalkylene ethers may be prepared by any known process such as, for example, the process described by Wurtz in 1859 and in the Encyclopedia of Chemical Technology, volume 7, pages 257-262, published by Interscience Publishers in 1951 or in US. Patent 1,922,459.

Any suitable polyhydric polythioether may be used such as, for example, the reaction product of one of the aforementioned alkylene oxides used in the preparation of the polyhydric polyalkylene ether with a polyhydric thioether such as, for example, thiodiglycol, 3,3- dihydroxy propylsulfide, 4,4'-dihydroxy butylsulfide, 1,4(beta-hydroxy ethyl)phenylene dithioether and the like.

Any suitable polyacetal may be used such as, for example, the reaction product of an aldehyde with a polyhydric alcohol. Any suitable aldehyde may be used such as, for example, formaldehyde, paraldehyde, butyraldehyde and the like. Any of the polyhydric alcohols mentioned above with relation to the preparation of hydroxyl polyesters may be used.

In the preparation of the organic compound containing active hydrogen containing groups, as determined by the Zerewitinofi method, the compounds preferably should have an hydroxyl number no greater than about 300 and preferably between from about 40 to about 200 and a molecular Weight between about 500 and about 30-00. The organic compound containing active hydrogen containing groups is admixed with an excess of an organic polyisocyanate to prepare a compound containing terminalNCO groups.

Any suitable organic polyisocyanate can be used in the preparation of the polymers such as, for example, toluylene diisocyanate or its isomeric mixtures, the uretdione of toluylene diisocyanate, 1,5-naphthylene diisocyanate, 4,4-diphenylmethane diisocyanate, the triisocyanates such as, tri-(4-isocyanatophenyl)thiophosphate, tri-(4-isocyanatophenyl)methane, the reaction products of polyhydric alcohols with an excess of polyisocyanate, such as, for example, the reaction product of 1 mol hexanetriol and 3 mols toluylene diisocyanate. Further, the isocyanates in the form of their adducts which can be split off under the action of heat can be used with particular advantage. These isocyanates are commonly referred to as masked isocyanates. The addition of the polyfunctional compounds is thereby substantailly facilitated since the spinning solutions are stable and capable of being stored at room temperature. Any compound such as, for example, phenol, cresol, hydrocyanic acid, bisulphites, acetoacetic ester, malonic ester, acetyl acetone and the like are suitable in the preparation of masked isocyanates by reaction with any known isocyanate. Further, the polyisocyanate used in accordance with this invention by adding to the spinning solution can be stabilized at room temperature by the addition of sulphurous acid. Of course, any other suitable polyisocyanate may also be used such as, for example, hexamethylene diisocyanate, cyclohexylmethylene diisocyanate, furfurylidene diisocyanate, xylylene diisocyanate and the like.

Any suitable solvent which is inert to both the hydroxyl compounds and the isocyanates may be used such as methylethylketone, diethylketone, methylpropylketone, dipropylketone, methylisobutylketone, butylacetate, dipropylether, dioxane, tetrahydrofuran, chlorobenzene, dichlorobenzene, dimethyl formamide, alcohol, methylene chloride, ethyl acetate, acetone, water and the like.

Any substance which will cause a condensation or radical cross-linking in the shaped element after the shaping operation may be used in the process of this invention. These substances are incorporated into the solution prior to shaping and can be added in the dissolved or undissolved form. The substance, however, must be compatible with the solution.

The crux of the invention resides in the fact that during the orientation by stretching, or in other words, in the oriented state, the fiber or film is fixed in that oriented state by some cross-linking. This is done by adding crosslinking agents to the spinning solution which are compatible therewith but will not react before the spinning process. The spinning material contains chemical groups which are able to react with the cross-linking agent at the desired moment. The desired moment is reached, when after spinning, the fiber or film is stretched. The fiber or film having been oriented is now subjected to the crosslinking action by a source of energy, which depending on the type of cross-linking action can be heat, radiation or both. The types of cross-linking action are condensation or radical reaction. Types of cross-linking agents useful therefore are polyisocyanates, blocked polyisocyanates, formaldehyde or derivatives reacting like a liberating formaldehyde on the one hand and radical reactions initiating substances such as peroxides and azonitriles. Both types of cross-linking actions can easily be combined.

The quantity of the substance utilized should be from about 0.1 to about 30 percent by weight of the solvent in the solution. More particularly, it should be from about 0.5 to about 10 percent of the weight of the polymer present. As stated above, any suitable compound which will cause condensation or radical cross-linking in the shaped element may be used such as, for example, formaldehyde derivatives such as a 40% formalin solution, urotropin methylal, urea formaldehyde resins, semiacetals of formaldehyde with polyols such as ethylene glycol, trimethylolpropane; polymethylol ethers such as melamine hexamethylol methyl ether; a copolymer of 0.75 part of methyl methacrylate and 25 parts of methacrylamide methylol methyl ether; acrylonitrile formaldehyde condensation products such as triacryl formal, methylene bisacrylamide and the like; diepoxides of glycols or diphenols and epichlorohydrin, a reaction product of gamma, gamma'-diaminopropyl-N-methylamine, and 4 mols of diane bis-epoxide; polyfunctional compounds with different functions such as, for example, ethyl methacrylate-alpha-isocyanate; mixtures of the above, such as, for example, melamine hexamethylol methyl ethers admixed with a masked triisocyanate, such as the reaction product of 3 mols of actoacetic ester and 1 mol of tri- (4-isocyanatophenyl)thiophosphate and the like. Also suitable for use in the process of this invention is any radical-forming substance which decomposes into radicals or which produce radicals at elevated temperatures under the action of radiation may be used such as, for example, dialkyl peroxides such as ditertiary butyl peroxide, dicumyl peroxide, diacyl peroxides such as dibenzoyl peroxide, diehlorobenzoyl peroxide; hydroperoxides such as cumyl peroxide, peracids such as perbenzoic acid; azo compounds of the azo-isobutyric acid nitrile type and redox systems such as ferric compounds and peroxides. The radical-forming substance can be stirred, pumped or sprayed into this solution in a diluted or undiluted form.

In many cases, it is desirable to incorporate into the polymers to be subjected to the shaping operation groups which preferentially react with the cross-linking agents for example, bis-oxyethyl-m-toluidine, 1,4-phenylene bisoxyethyl ether and the like.

In the case where substances which produce a radical cross-linking in the product are used, it is advisable to provide olefinic double bonds, alpha-carbonyl activated double bonds, tertiary carbon atoms or active methylene groups in the polymer. These can, for example, originate from the following substances used in the isocyanate polyaddition process; butanediol, maleic acid, dihydromuconic acid, acrylic and methacrylic acid diethanol amides, (N-acrylic acid)- or (N-methacrylic acid ethyl ester)-N'-(bis-oxyethyl)-urea. The latter can be obtained by the conversion of acrylic or methacrylic acid ethyl ester isocyanates with diethanolamine, or the analogous urea diols of the said unsaturated isocyanates with 2- amino-Z-methyl-l,3-dihydroxy propane.

The olefinic double bonds activated by alpha-carbonyl groups can be introduced into the polyaddition product by oxethylated dihydroxychalcones such as 4,4'-bis-oxyethyl ether chalcone, 4,4'-dioxethyl distyryl ketone, oxethylated dicarboxylic acids such as cinnamic acid-pcarboxylic acid-bis-oxethyl ester and 1,4-phenylene bisacrylic acid oxethyl ester.

The tertiary carbon atoms can, for example, originate from 4,4'-bisoxethyl ether diphenyl methyl methane, 3- methyl pentane-2,4-diol, butane-1,3-diol or hexane-2,5- diol. The activated methylene groups can, for example, originate from diphenyl methane derivatives, such as 4,4- diphenylmethane diisocyanate or 4,4-bisoxethyl ether diphenylmethane.

In addition to the olefinic double bonds incorporated in the polymers to be shaped, the solution of these polymers can, with advantage according to the invention, have incorporated therein other substances containing several vinyl or allyl groups which are able to undergo homopolymerization or copolymerization under the action of radicals and thus can cause a cross-linking of the initial material after shaping into a filament or film. Examples of compounds suitable for this purpose are triallyl phosphate, triallyl cyanurate, divinyl benzene, divinyl sulphone, triacryl formal and methylene bisacrylamide.

In order to activate the cross-linking in the shaped element, the cross-linking is initiated by ultra-violet light, sensitizers such as benzophenone can be added to the composition prior to shaping.

The solution can also have incorporated therein dyestuffs, stabilizers and pigments such as T10 The shaping from the solutions, for example, the spinning, is effected in a manner known per se. A spinning solution is supplied by way of a proportioning pump and spun from a multiaperture spinneret into a vertically disposed funnel with a length of 2 to 5 meters. Hot gases or vapors such as air, nitrogen, carbon dioxide or steam can be injected into the funnel from below. The funnel temperature is between approximately 100 and 250, preferably about 130 to 180, and the air temperature is kept at a lower level, such as between 80 and 230, preferably between 100 and 160. The filaments leaving the funnel run over a roller system having the speed v (v c=v The final cross-linking of the filament, band or film takes place according to the process of the invention either by heating to elevated temperatures or by heating and simultaneous exposure to radiation or solely by the action of radiation. In the case where heating is used, the filament is either guided through a heated tube, or the package of filaments is introduced on the spool or bobbin into a heating chamber.

The temperatures should be between 50 and 150 C., more particularly between 75 and 120 C. and the heating should last between 5 and 60 minutes, more particularly between 5 and minutes. In the case where radiation alone is used, or where additional radiation is employed, the filament is exposed to the light of an ultra-violet source, for example, a mercury lamp or a carbon arc lamp. However, an incandescent lamp of high candle power can be used as light source. The filament is led past the light source which is at not too great a spacing therefrom in such a manner that it is exposed to the radiation for at least 30 seconds.

The invention is further illustrated by the following examples in which the parts are by weight unless otherwise specified.

Comparison example About 200 parts of a polyester of ethylene glycol and adipic acid having an hydroxyl number of about 56 are reacted for about 60 minutes at about 130 C. with about 80 parts of 4,4'-diphenylmethane diisocyanate. The melt is taken up in about 100 parts of methyl ethyl ketone, a solution of about 80 parts of butane-1,4-diol and about 0.8 milliliter of dimethyl cyclohexylamine in about. 75 parts of methyl ethyl ketone is added and reaction is allowed to take place for about minutes at about 80 C. The solution is thereafter diluted with about 150 parts of dimethyl formamide and the reaction is terminated by adding about 2.0 parts of diethanolaminc in about 25 parts of dimethyl formamide. The 46 percent highly viscous spinning solution is spun at a delivery rate of about 3.0 milliliters per minute through a 16 aperture spinneret (bore diameter about 0.10 millimeter) from above into a heated funnel. The funnel has a length of about 4.5 meters and a diameter of about 200 millimeters and is heated to about 150 C. About 10 to 12 cubic meters of air per hour heated to about 110 C. and charged with finely atomized talcum are introduced from below into the vertically disposed funnel. On leaving the latter, the filament is conveyed over a driven guide roller running at about 40 meters per minute and is wound at a speed of about 44 milliliters per minute. The orientation imparted to the filament is about 1.1 being thus very slight at about 10 percent.

Orientation 1.1 Titre denier 320 Elongation percent 720 Tensile strength grarns/denier 0.3 E-rnodulus do 0.035 Permanent elongation at percent- 8.5

EXAMPLE 1 About 9.5 parts of the acetoacetic ester adduct of tri- (4-isocyanatophenyl)thiophosphate are incorporated by stirring into about 450 parts of the spinning solution described in the comparison example, just before the spinning thereof, and the spinning is carried out as described with a delivery rate of about 2.4 milliliters per minute from an 8 aperture spinneret (bore diameter 0.20 millimeter) and a discharge speed V of about 40 milliliters per minute. The filament is wound at about 80 and about 200 milliliters per minute respectively and is heated on the spool for about 30 minutes at about 120.

If filaments fixed in this way are dipped for about 10 minutes into boiling water, the mechanical values given above are not changed.

EXAMPLE 2 About 40 parts of the malonic acid-diethylester adduct of tri-(4-isocyanatophenyl)thiophosphate are incorporated by stirring into about 450 parts of the spinning solution described in the comparison example, just prior to the spinning thereof, and spinning is carried out as described at a delivery rate of about 2.4 milliliters per minute from an 8 aperture spinneret with a bore diameter of about 0.20 millimeter. The discharge speed v is about 40 milliliters per minute as in Example 1; for the final cross-linking, the filament is subjected to a temperature of about for about 30 minutes.

EXAMPLE 3 About 2.0 parts of triacryl formal are dissolved with stirirng in about 450 parts of the spinning solution described in the. comparison example, priorto the spinning thereof, which takes place in accordance with Example l. The elastic filament is heated on the spool for about 30 minutes to about 100 in a heating chamber.

EXAMPLE 4 About 200 parts of the polyester described in the comparison example are melted for about 60 minutes with about 80 parts of a 4, 4-diphenylrnethane diisocyanate at about 130 C. A solution of about 16.20 parts of butane- 1, 4-diol, about 15.60 parts of N-(beta-methacrylic acid ethyl ester)-N-(bisoxethyl)-urea and about 0.8 milliliter of dimethyl cyclohexylamine in about 65 parts of methyl ethyl ketone is added to the resulting melt in about 100 parts of methyl ethyl ketone. The reaction mixture is kept for about 20 minutes at about 80 C. The viscous mass which forms is diluted with about 155 parts of dimethyl formamide and the reaction is terminated by adding about 1.5 milliliters of diisobutylamine in about 10 parts of dimethyl formamide.

About 1.0 part of azo-isobutyric acid nitrile is incorporated by stirring into about 450 parts of this spinning solution prior to the spinning thereof. Spinning is carried out in a manner similar to Example 1 with a delivery rate of about 1.8 milliliters per minute from an 8 aperture spinneret with a bore diameter of about 0.20 millimeter and a delivery speed v of about 40 milliliters per minute. The filament is wound at about 180 milliliters per minute. The filament package is thereafter heated on the spool for about 30 minutes to about 70 in a heating chamber.

Orientation 4.5 Titre clenier 50 Elongation percent 430 Tensile strength "grams/denier" 0.26 E-modulus do 0.11 Permanent elongation at 100% percent 4.8

EXAMPLE 5 About 1000 parts of an adipic acid-ethylene glycol/butanediol copolymer (molar ratio of the glycols 1:1; OH number 55.0; acid number 0.7; Water content 0.01%) are mixed with about 90.3 parts of butane-1,4-diol, about 14.4 parts of titanium dioxide and about 0.31 part of ferric acetyl acetonate at about 60 and about 400 parts of diphenylmethane-4,4-diisocyanate are quickly added while stirring. After about three minutes, the melt is poured into shallow trays and subsequently heated for about minutes in an oven heated to about 110 C., and thereafter, the already solidified polyurethane composition is removed and granulated after cooling.

In order to produce a spinnable elastomer solution, about 660 parts of granulated polyurethane with a mvalue of 1.26 (measured in hexamethyl phosphoramide, C 1 g./100 ml.) are added in portions to about 2340 parts of dimethyl forrnamide at about 60 to about 70 C. while stirring, and kept at this temperature until complete solution has occurred. The viscosity of the solution is 925 p/ C.

About 13.2 parts of melamine hexamethylol ether dissolved in about parts of dimethyl formamide are added to about 1250 parts of the aforesaid solution and homogenized by stirring. The solution is heated to about 50 C. and while being advanced at a speed of about 8.7 ml./1nin. through a nozzle plate with 16. holes of a diameter of 0.2 mm., is spun into a shaft with a length of 5 m. and heated to about 250 C., in which air heated to about 240 C. is blown from above. The filaments are Withdrawn from the shaft at a speed of about m./min., treated with an aqueous suspension containing 10% of talcum by means of a roller and wound onto spools at a speed of 82 m./min. (practically without stretching) or at m./min. (50% stretching). The filaments are heated on the spools in a drying chamber for 2 /2 hours to 110 C. The solution is spun in the same manner without any additive (comparison experiment); the filaments are heated for 2 /2 hours on the spool at 110 C.

The properties of the fibers, with and without addition of the cross-linking agent, are set out side by side for comparison purposes in the table.

2% Addition Without Addition Stretching Tensile strength, g./den 0.83 0. 88 0.85 0. 9! Elongation, percent 650 500 640 530 Modulus (300%), mg./(len.:

1st cycle 90 192 92 200 2nd cycle 80 176 81 172 3rd cycle 77 165 75 161 Modulus rug/den.

3rd cycle (relaxation cycle) 16 22 16 23 Permanent elongation, percent,

3X300% after 30 seeonds 22 14 2O 18 Shrinkage on boiling, percent,

10 min., 08 1.5 3 2.0 12 Permanent elongation, percent, after heating for 10 minutes to 98 14 22 Where filaments have hereinbefore been referred to, the information given similarly applies to the regulation of the elasticity modulus of strips and foils.

Although the invention has been described in considerable detail for the purpose of illustration, it is to be understood that variations may be made therein by those skilled in the art without departing from the spirit of the invention and the scope of the claims.

What is claimed is:

1. A process for the preparation of shaped polyurethane polymer which comprises preparing a solution of a polyurethane polymer in an inert solvent, said polyurethane polymer being the reaction product of an organic compound containing active hydrogen atoms, which are reactive with NCO groups and an organic polyisocvanate, said solution being substantially free of -NCO groups, introducing into said solution a compound compatible therewith and capable of reacting with said polymer only upon imparting energy thereto, shaping said solution through a shaping aperture, stretching said shaped polymer and applying energy thereto to cause cross-linking in the stretched condition to thereby fix orientation.

2. The process of claim 1 wherein said compatible substance is selected from the group consisting of organic polyisocyanates, formaldehyde, organic peroxides and azonitriles.

3. A process for the production of elastomeric polyurethane fibers which comprises preparing a spinning solution by reacting in an inert solvent therefor, an organic compound containing active hydrogen atoms which are reactive with -NCO groups and an organic polyisocyanate until the solution is substantially free of NCO groups, introducing to said solution a compound compatible therewith and capable of reacting with the polymer thus formed only upon the application of energy, spinning said solution through a shaping aperture to form fibers, stretching said fibers and applying energy thereto to cause cross-linking in the stretched condition to thereby fix the orientation.

4. A process for the production of elastomeric polyurethane fibers which comprises preparing a spinning solution by reacting in an inert solvent therefor, an organic compound containing active hydrogen atoms which are reactive with NCO groups and selected from the group consisting of hydroxyl polyesters, polyhydric polyalkylene ethcrs, polyhydric polythioethers and polyacetals and an organic polyisocyanate until the solution is substantially free of NCO groups, introducing to said solution a compound compatible therewith and capable of reacting with the polymer thus formed only upon the application of energy, spinning said solution through a shaping aperture to form fibers, stretching said fibers and applying energy thereto to cause cross-linking in the stretched condition to thereby fix the orientation.

5. A process for the production of elastomeric polyurethane fibers which comprises preparing a spinning solution by reacting in an inert solvent therefor, an organic compound containing active hydrogen atoms which are reactive with NCO groups and an organic polyisocyanate until the solution is substantially free of NCO groups, introducing to said solution a compound compatible therewith and capable of reacting with the polymer thus formed only upon the application of energy, said compound being selected from the group consisting of organic polyisocyanates, formaldehydes, organic peroxides and azonitriles, spinning said solution through a shaping aperture to form fibers, stretching said fibers and applying energy thereto to cause the cross-linking in the stretched condition to thereby fix the orientation.

6. The process of claim wherein the group member is the acetoacetic ester adduct of tri-(4-isocyanatophenyl) thiophosph ate.

7. The process of claim 5 wherein the group member is the inalonic acid diethyl ester adduct of tri-(4-isocyanatophenyl) thiophosphate.

8. The process of claim 5 wherein the group member is triacryl formal.

9. The process of claim 5 wherein the group member is azo-isobutyric acid nitrile.

10. The process of making a cured elastomeric thread comprising dissolving 100 parts by weight of an uncured polyurethane polymer, which is a reaction product of a material containing hydroxyl groups, said material being selected from the groups consisting of polyesters, polyesteramides, polyethers and polyesterethers, plus free glycols, with a sutficient amount of an aromatic diisocyanate to react with essentially all of the hydroxyl groups present, in a solvent therefor, adding to the polyurethane polymer solution from 0.5 to 10.0 parts by weight, based on the weight of said polyurethane polymer, of a free radical initiator selected from the group consisting of benzoyl peroxide and halogen substituted benzoyl peroxides, extruding said solution through an orifice to form a monofilament, and curing said monofilament by ex- 12 posing it to heat in the range of C. to 150 C. for from 5 minutes to 60 minutes in air.

11. The process of making a cured filament comprising preparing a 40% to 50% by weight solution in a solvent selected from the group consisting of acetone, tetrahydrofuran and dimethylformarnide, of a polyurethane polymer which is a reaction product of a material containing hydroxyl groups, said material being selected from the group consisting of polyesters, polyesteramides, polyethers, and polyesterethers, plus free glycols, with a sufficient amount of an aromatic diisocyanate to react with essentially all of the hydroxyl groups present, adding from 0.5 to 10.0 parts by weight per parts by Weight of said polyurethane polymer of a material selected from the group consisting of benzoyl peroxide and halogen substituted benzoyl peroxides, extruding said polymer solution through an orifice to form a monofilament and curing said monofilament by exposing it to heat. in the range of 80 C. to C., for from 5 minutes to 60 minutes in air.

References Cited UNITED STATES PATENTS 1,976,348 10/1934 Joss 26420l 2,052,361 8/1936 Pestalozza 264-210 3,009,764 11/1961 Urs 264-184 3,036,878 5/1962 Polansky. 3,047,356 7/ 1962 Polansky. 3,054,756 9/1962 Holtschmidt et al. 26077.5 3,087,912 4/1963 Wagner et a1 260-77.5 3,097,192 7/1963 Schilit 26077.5 3,105,062 9/1963 Graham et al. 26077.5 3,120,502 2/1964 Merten 26077.5 3,130,175 4/1964 Odenthal et al. 26077.5 3,154,611 10/1964 Dinbergs 264--176 FOREIGN PATENTS 110,835 6/1940 Australia.

OTHER REFERENCES Rinke, Elastomeric Fibers Based on Polyurethanes, Angew. Chem. internat. edit, vol. 1, (1962) No. 8, pp. 419 to 424, (copy in Sci. Lib.), (also 26077.5 Spandex).

ALEXANDER H. BRODMERKEL, Primary Examiner.

ROBERT F. WHITE, D. J. ARNOLD, Examiners.

K. W. VERNON, A. L. LEAVITI', Assistant Examiners. 

1. A PROCESS FOR THE PREPARATION OF SHAPED POLYURETHANE POLYMER WHICH COMPRISES PREPARING A SOLUTION OF A POLYURETHANE POLYMER IN AN INERT SOLVENT, SAID POLYURETHANE POLYMER BEING THE REACTION PRODUCT OF AN ORGANIC COMPOUND CONTAINING ACTIVE HYDROGEN ATOMS, WHICH ARE REACTIVE WITH -NCO GROUPS AND AN ORGANIC POLYISOCYANATE, SAID SOLUTION BEING SUBSTANTIALLY FREE OF -NCO GROUPS, INTRODUCING INTO SAID SOLUTION A COMPOUND COMPATIBLE THEREWITH AND CAPABLE OF REACTING WITH SAID POLYMER ONLY UPON IMPARTING ENERGY THERETO, SHAPING SAID SOLUTION THROUGH A SHAPING APERTURE, STRETCHING SAID SHAPED POLYMER AND APPLYING ENERGY THERETO TO CAUSE CROSS-LINKING IN THE STRETCHED CONDITION TO THEREBY FIX ORIENTATION. 